The present invention relates to erosion determination and more particularly, to an improved means for providing an accurate indication of the corrosion rate in operating equipment to facilitate meaningful inspection of such equipment for determining when refractory lining replacement should take place.
In those instances such as in catalytic cracking units and other petroleum process operations, the equipment employed typically has an interior lining such as a refractory lining. These linings are particularly important to the proper operation of the equipment including maintaining the heat within the particular piece of equipment, as well as preventing the outer shell of the body from being damaged due to the excessive heat. It is typical to line such equipment with a refractory material and to employ various types of means in order to determine the rate of erosion of the lining so that the lining can be replaced when it has gone from its original thickness to an eroded thickness which is below a predetermined replacement value. Presently, various unsatisfactory methods and techniques for determining the erosion rate are employed, none of which provide an accurate, simple and inexpensive erosion rate determination indicator which can be applied to all types of refractory linings and for any lining thickness.
Prior art techniques include those which are not only complex and costly, but are also sensitive to physical damage and are unreliable especially when installed in equipment such as cyclones. For example, U.S. Pat. No. 3,842,792 discloses a visible monitor indication for determining seal wear in a combustion engine; however, the device disclosed is not applicable to where impingement and erosion takes place over an entire surface but rather to a particular location.
Other devices are disclosed in U.S. Pat. No. 2,915,305 which discloses an embedded thermocouple responsive to temperature changes for providing information on the formation and shape of an eroded area in a blast furnace. Reliance on electrical conductivity changes indicate the progress of erosion. U.S. Pat. No. 3,015,950 discloses an electrically sensitive sensor whose electrical properties are proportional to its length and is embedded in a body with its length corresponding to the thickness of the body. Erosion of the body and element occur simultaneously and thus, a decrease in length of the latter corresponds to the thickness of the body. U.S. Pat. No. 3,078,707 discloses a gage in a refractory wall of a blast furnace for measuring thickness of material and employing gradually eroded wires along with the erosion of the furnace wall for facilitating periodic measurements of the remaining thickness of the wall and the rate of destruction thereby being easily determined. Other patents such as U.S. Pat. Nos. 3,236,096 and 3,307,401 disclose other techniques for measuring the amount of erosion or wall thickness of a furnace, whereas U.S. Pat. No. 3,362,810 discloses physical arrangement for visible indication of corrosion, destruction or erosion.
None of these prior art techniques, however, disclose an arrangement which provides for visible indication of erosion of a specific and/or overall surface area by exposure of increasingly greater portions of a non-destructive member which is indicative of the erosion and aids in determination of the remaining thickness. Such a device would be relatively simple, economical and not sensitive to physical damage and have applicability for all types of linings, refractories and otherwise. An arrangement of these devices within a unit such as a cyclone can establish accurate erosion profiles.